code: def test_custom():
      comm = create_communicator("naive")
      try:
          check_custom(comm, 97, 7)
          check_custom(comm, 9, 77)
      finally:
          comm.finalize()
  
file_path: chainer/tests/chainermn_tests/extensions_tests/test_multi_node_evaluator.py
imports: import chainer
  import chainer.testing
  from chainer.datasets import TupleDataset
  from chainer.iterators import SerialIterator
  from chainermn import create_communicator
  from chainermn.extensions import GenericMultiNodeEvaluator
label_desc: Use image node_id 4 for calling a global function with example usage: test_custom() without return types